Electromyography (“EMG”) is a technique for evaluating and recording the electrical activity produced by muscles within the body. Such electrical activity (also referred to as an “EMG response”) may be produced in response to application of a stimulation event (e.g., an electrical stimulation pulse train) to the muscle and/or to some other bodily structure neurologically associated with the muscle, and, in some instances, may be characterized by involuntary movement of the muscle in response to the stimulation event. EMG responses may be analyzed to set one or more control parameters governing an operation of an implantable stimulator, detect medical abnormalities, determine activation levels, and/or perform a variety of other medically related tasks associated with a patient.
To illustrate, EMG responses generated by the stapedius muscle are often referred to as “stapedius reflexes” and may be used to objectively determine one or more most comfortable current levels (“M levels”) for a cochlear implant patient. An M level refers to a stimulation current level applied by a cochlear implant system at which the patient is most comfortable. For example, a current level of electrical stimulation applied by a cochlear implant system to a patient may be increased until a stapedius reflex (i.e., an involuntary contraction of the stapedius muscle) is elicited. The current level required to elicit a stapedius reflex within the patient (referred to herein as a “stapedius reflex threshold”) may then be used by a clinician as a starting point for determining an M level corresponding to the patient.
Unfortunately, some types of EMG responses (e.g., stapedius reflexes) are often difficult to detect. For example, some EMG responses have relatively low signal levels, and can therefore be difficult to distinguish from noise and stimulus artifacts that may be present in a recorded EMG signal that contains an EMG response.